Gassy and stomach has been feeling really sick. did have sex on the 14th.

Probably gastritis: you probably ate something which is irritating your stomach or early viral infections I do not think having sex on 14th is the cause unless you are stressing over it causing the nausea Wait a few days and se how you do You can use OTC medications to help with the gas and nausea If it increases in nature then see provider

Unrelated : Your sexual encounter and intestinal symptoms are likely un related. U may have contracted a viral illness. Try some over the counter antacid, to see if they help. If symptoms persist after about 2 days, you should be seen by a doctor.