sore head of penis

had sexual contact with a female 30 months ago.about 3days later got a sore head of penis,iv’e had all tests done on 3 separate occasions and seen 2 urologists but everything negative.just been to Clare well private gum clinic they diagnosed lichen sclerosis been on clobetasol cream for about 3weeks but no sign of improvement yet any body know how long it takes for improvement ? And can you get lichen sclerosis that quick .read it was a gradual disease