Eat smaller light meals more frequently instead of big ones and drink plenty of water. Depending on the antibiotic you might be able to take an antacid such as Tums. You could try some of the anti nausea wrist bands they sell at most drug stores, their like sweat bands but have a little ball on them that applies pressure on each wrist. Their usually only like $10 and are reusable as long as you take care of them. Not sure if they actually work but I've used them a few times and they seemed to be alright but it could just be a mental thing. Also anything with ginger should help (crystallized ginger, ginger tea, ginger ale, etc.) If the nausea is really bothering you you could talk to your doctor about it and he/she might be able to prescribe another antibiotic.