My Husband Is Taking Amoxacillin For A Chest Infection /

My husband is taking amoxacillin for a chest infection / virus. He has many other medications with no side effects. To date he has taken the amoxocillin 3 times a day for 115 days. Yesterday perfect round spots appeared on his buttocks looked opake small round spots appeared down his inside thigh and today up both thighs from the top near the groin. The original spots have now bled into red plaques.
Trying not to bother our surgery advice please. My Husband is 85 and has had medication after corrotid artery surgery in 1999.