My 8 week old sure cries alot...?

I am a first time mommy and my 8 week old son man does he cry alot! I suspect its colic? He also has a rash on his face and now on his head, he has an appointment on Friday to see the dr..I wonder if her has a milk protein allergy? I usually have to hold him alot during the day, he sleeps kay at night, he was fed for a little over a month and then was on Similac Advance Early Shield, but got gy alot so h is now on Similac Sensitive. gas is better but still cries alot. He cried alot the first night he came home....makes me feel like I'm doing something wrong sometimes. I can usually calm him down eventually but my husband usually cant...any ideas? Think its colic? If so when will this ease up? Could it be an allergy?