3.5 months update.
This is what I've concluded. SSRI does work for my POIS. It's not 100% but it make me able to function. With POIS, sleep is the only cure and I am more active with SSRI. However, the problem is still there. Like the previous poster said, I think lexapro is definitely doing something that is making my POIS better. W/o lexapro, I felt extremely exhausted within 10 minutes after O, and I just could not get up, function or feel any desire to do anything. I felt exhausted for the days after that. What lexapro does is that it lengthens that 10 minutes to about 1.5 hours and it is much less severe. I can actually work out, study or have another round if I desire.
Something happened during the time though. SSRI was prescribed to me due to my generalized anxiety as well. It's been working out great in that sense. I started on 5mg for 1 week and 10mg after. I felt like there was a room for improvement. Doc upped dosage to 15mg after 2 months on 10mg. 1 month into 15mg, I felt that there was something wrong with my body. My doc calls it "different form of anxiety attack", I have pharmacist and nurse friends, and they call it "mild serotonin syndrome", I was experiencing hypereflexia, anxiety, extreme ADHD, almost manic like state. I called doc immediately, doc wanted me to actually stay on 15mg since she thought it was an anxiety attack, but I felt unsafe and lowered dosage to 10mg. During that 1 month on 15mg, I didn't see much improvement on POIS. 10mg worked better than no SSRI though. I've been on 10mg for a month now, the weird side effect that I encountered from 15mg disappeared and I am back to normal.
In retrospect, I try to remember how I used to feel and compare now and then. I am also diagnosed ADHD. There is one big problem that came up with the use of SSRI. SSRI killed my anxiety, which was a big problem for me. However, SSRI acted like a double edged sword; without anxiety, I found myself no longer motivated to do anything, carry on responsibilities and chores. Simply, my ADHD got worse. I was on ritalin and focalin. For some reason, after 1 month on lexapro, the ADHD meds stopped working, it no longer gives me clarity and focus. All I get from ADHD meds are just a ton of side effects such as tightening of chest and shortness of breath and so on at even at very low dosage. I stopped taking ADHD meds because of side effects. Instead of giving me any positive effects from ritalin, I now find it extremely sedating and it puts me to asleep.
I work in healthcare, and I consulted about my situations with friends who are MDs as I have feel some changes to my mental and physical sensation. One brought up an interesting point that my metabolism is all messed up due to medications. I felt extremely sedated on 2.5mg of focalin while on lexapro. A friend asked me a couple of questions, suspected me to be hypoglycemic. Did the blood glucose level test, and it came out to be 71mg/dl (cutoff line is 70). This came to me as a shock. This was 1 hour after my lunch, my blood glucose level should be higher than 110. I am not the most active guy, I used to be very obese. I took a glucose tablet, and the symptoms went away. I frequently take my blood glucose level now and my blood sugar level is low, around 80-90s. This is not the way I usually am and this is a news to me. I had a physical and blood test a year ago and my blood glucose level was actually higher side on the normal range. For some reason, my insulin is overworking and I think norepi system is involved.
I had many hypotheses that didn't work out as I wanted them to be. Like LAPOISSE said, I think serotonine/dopamine is surely involved in POIS. Lexapro is a very selective SRI, but it does affect norepi reuptake at some extent. In the past year with a lot of trials on tons of drugs, I found out that I am extremely sensitive to stimulants, even coffee and vitamin B pills. Seeing how ritalin (and focalin) sedates me now that I am on lexapro is a mystery to me. ADHD meds usually work on reuptake of dopa and norepi. Doc assures me that there is no interactions between them, but I think otherwise. Maybe, the adrenergic regulation is in imbalance for some of us, causing anxiety, adhd and other symptoms including pois. Orgasm releases a ton of hormones and that can really mess up brain chemical imbalance. I read somewhere that O can be like a panic attack which is followed by extreme sedation of the body. Someone mentioned clonidine (a2 receptor agonist), I wonder if anyone tried it.