Pain on right hand side of stomach and my right arm feels numb and tingly i'm on penicillin could that be an effect to that?

It all depends : At 31 gastritis likely due to alcohol or Aspirin like substances , treated with h2 blocker, proton pump inhibitors , or protective like sucralfate , and withdrawal of the substance a bacterial infection like h.Pylori need antibiotics for 10 days , rarer autoimmune like that cause B12 deficiency need blood work , and by the way can cause tingling need supportive treatment and vitamin replacement.