Powders with paracetamol and aspirin seem to induce nausea and stomach pain. is this a normal effect on the aspirin on the ulcer, or am i allergic to aspirin?

Aspirin and ulcer: Do not mix at all. You could have a massive bleeding.

No aspirin: Anyone with an ulcer should not take Aspirin because it could enlarge the ulcer and cause the ulcer to bleed inwardly lot to perforate and bleed into the abdomen. Paracetamol is safe.. Get well soon.

Nausea: Aspirin can cause nausea. That is why they produce enteric coated aspirin.