Have painful teeth, ear infection, bacterial infection. On similac alimentum. Help?

7 mo old boy, whom is ALWAYS happy no matter what, i have only seen him have tears twice & has never made a fuss until this week. has acid reflux (takes Zantac daily since 1 mo old), he's been on similac alimentum since 2 mo, just started baby food about 2 weeks ago, did ok at first, but the last few days he's very unhappy, grunting, screaming, gets these looks on his face like something is really hurting him. Even while his first two teeth came through he never acting anything like this. Took to doc, said he had small ear infection. They seemed to ignore that I told them his urine has been dark and smells aweful! I think it's a bacterial infection in his belly but I don't know. He's never had a fever either.