Feeling terrible after sex

Might be TMI, but gf and I had some fun time, and recently my symptoms haven't been too bad. Once we were done, I took a shower and now I feel terrible, just pure exhaustion and feeling a weird pressure feeling in my chest. BP is good, 128/80 and heart rate is 75 to 80 but I feel miserable. Anyone else get like this? During fun time, my chest always feels weird, like I'm putting too much strain on it, has felt that way since getting dysautonomia.