My very normal looking freckles often swell and itch. When they swell they look like a mole, round and dark, and itch like a mosquito bite. The next day they're back to a normal freckle. Sometimes just one freckle and sometimes many of them. It does happen only to the larger freckles but not consistently to one and not the others. I had one biopsied once and it was cleared of any medical concerns. Just want to know what causes it in hopes of avoiding triggers as it is so irritating.