What to do if i have a blister in my mouth(about 3-4), it opened last night & bleed, now closed. i have hfmd. is that bad!?

HFM: Hand foot and mouth, right. The blisters are the 'mouth' part. They're like canker sores, they can open, and bleed, but only a little. They're viral and usually resolve, without treatment, in about a week. Try something for pain. Cool things will sooth your mouth, like pudding and ice cream.

Blister care: You mean Hand-foot-mouth disease by hfmd right? It happens more to kids but since it is a viral infection I suppose anybody can get it. The blisters in your mouth and the rash on the hands and feet and other parts of your body will go away in a few days. I advise parents to mix equal parts of Benadryl (diphenhydramine) and Maalox (or other antacids) and rinse your mouth. It may help the pain.