I'm taking Zpak for my illness. I took the first double dosage ye...

I'm taking Zpak for my illness. I took the first double dosage yesterday during school and it really messed with me. At one point, I felt like I was going to throw up, though most of the time I didn't feel like my normal self. I laughed at things that weren't funny and just had laughing attacks. I believe I saw things that didn't exist as well. I took another pill today and it left me feeling like someone was stabbing my stomach. However, right now I feel fine, just a little tired and hungry. Is it possible that I'm having an allergic reaction or the Zpak is reating with other medication I'm taking, like Prozac? It makes me feel very off, but it's hard to describe.