What Can I Do About Dark Spots from Insect Bites and Keloid Scar?

I have dark spots on my arms, legs, and thighs from flea insect bites. I also have a 8-inch long scar on my right leg starting from the middle of my knee and going down. Some of the scar is keloid. I've tried all sorts of prescription creams for the spots and recieved no luck. I've also tried injections for the scar and haven't seen much difference. What should I do about this? How much do you think it would cost?