My Grandson just had an abscess lanced on his butt, The doctor said that is was a staph infection but did not tell us what kind of staph infection although I believe that it is MRSA . He also has multiple sores on his tongue and his gums are very red. He is taking 2 antibiotics, bactrim and keflex, while also taking tylenol with codeine . Will MRSA cause the sores on his tongue and red gums? Will the medicine he is taking cause either of these? He has only been on the meds for 24 hours. He has to return to the doctor tomorrow to remove the packing from the incision. How concerned to I need to be for the sores on his tongue and red gums. His appetite has certainly dropped.