My 12 year old has his second methotrexate injection on Thursday night. He just woke up tonight with ear pain so my husband took him to ER because he was in so much pain. They gave him a dose of amoxicillin and he is back home sleeping now. However, after reading online, it seems to be a big no-no with the methotrexate. Has anyone else had children take amoxicillin while on methotrexate?