vic_m has a good suggestion in avoiding sex for a while to help give it a chance to let it heal. If that doesn't work, it would be a good idea to have a doctor look at it to see why it's not healing, you would want to see if there's an infection or other allergy/eczema that could be causing it to be weak there.
sounds like you're describing a cut on the foreskin as it gets pulled over the head, but it's tight so it tears? if so you may be suffering from a condition called phymosis, for which your urologist can help.
if not, then you are describing something that is the result of mechanical stress. in that case, you could stop having sex for a while and let it heal properly. you should keep up with the topical antibiotic/band aids because that's an area that can help bacteria live (warm, dark, moist).
at the first sign of infection- redness, swelling, warmth (more than normal), discharge from the cut, fever (in association with these)- and you should head to the ER.