From 3-4 months I'm noticing a discolored (whitish) area on my penis head, it is non-itchy, probably not growing or growing very slowly. What is it?

Here are some ... The described whitish spot is most likely benign; so, continue your careful watching as described, but not over-bearing and obsessed. The key points of watching is its size, color, local induration, edge elevation, bleeding, etc. Should something be done with it? No, at this time and reviewing this spot in 4-6 months would be adequate.