Hello,
This can be due to having intercourse after meals. First of all, have a gap of around 2 hours between meals and retiring to bed. Also try raising the head of your bed about four inches with blocks. It also might help to avoid eating or drinking for two hours before you lie down. To help control the stomach acid, one should not drink alcohol or drinks with caffeine in them, or eat chocolate or spicy or greasy foods .
Take some OTC antacid like Mylanta. You can also take zantac(ranitidine)or prilosec(omeprazole).These will help. Also keep your fluid electrolyte balance optimum by drinking lots of fluids.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
I get sick after sex also ... I feel lightheaded and sometimes i feel like I'm going to puke