What cause painful pinkish inner/dark red edges patch with a pea size lump underneath it? Located on the lower inner right thigh close to knee.

Shingles? Without being able to look at it, i would hesitate to attempt a diagnosis. That being said, if it is painful, and has a "blister" look about it, it could be shingles, which can be treated. Get it looked at soon as getting on the antivirals for it sooner would give a better outcome. If, of course, it is shingles.