thought I was about to be ill, worried the feeling may come back

Hi,
I am not really sure what happened. I was at the Gym today and everything was fine, I went on the rowing machine for 10 minutes which seems to have stretched some muscles in my stomach and is admittedly making it ache. I came back incredibly hungry and ate and drank porridge, tea, a roll and a smoothie. I don't know why but it didn't seem to settle too well, I got this very quivery feeling in my stomach (which I personally associate with being ill) and it felt like it was rising. I completely panicked, took a stomach tablet and it has calmed down a little, but I am worried it will come back! Could it or would it work through the tablet if it was a bug?
I also wanted to ask if you walk past you know what in the street can you get it? I sometimes wonder if it could just be a drunk person but today I managed to walk past at least 3 of that and I was worried I could catch it from being so near it.

Both my husband and I can't eat too soon after working out. If we do we feel sick. It could be that. Maybe wait a little longer to eat next time. I don't know what porrage is. Is it creamy and a heavy meal?