Suggest Treatment For Red And Purple Blotches On Upper Arm

1-2 years ago I got these red/purple blotches on my upper arm and it's always present but the severity differs from day to day, I took picuters of my arm to show you but this has been worrying me because my health overall has been bad but I haven't got any answears, I've lost over 40 pound last year and a half and that's just very unlike me because I´ve always been overweight no matter what and all of sudden it's not like that any more, I just can't eat much any more, I always just seem to be able to eat small amounts at a time.

My symptoms are all so non specific I think that doctors don't have a clue what's wrong so I was wondering if you have any idea?