What Causes Fluid Filled Blisters On The Head Of Penis Post Intercourse?

After intercourse On the head in my penis I have what looks like two large blisters. They are not causing pain but are large and are attached either side of the head. Like water blisters. They haven t grown it s as if the side wall has filled with fluid. It s happened after intercouse before have went down after a few days. Is this normal?