Blister on toe

I’ve had, for several months, what looks like a corn on the top of my 4th toe but isn’t hard like one. It becomes inflammed and forms a thick skin. If expressed, a clear jelly like liquid comes out and eventually runs watery for a lttle while. For a time, it appears to be drying up then the process starts over. I’ve tried keeping it covered to protect it with bandaids, moleskin, etc, but it doesn’t help.Any ideas?