Bug bites won't heal

I have a lawn care business so I assume what I have is from a bug, a thorn, or the sun. Last year I had an itchy spot on my hand, it felt like a mosquito bite. I scratched it a little too much until it bled. I figured it would scab over and heal within a week or two. A couple months later I noticed it was still there unhealed. I reopened the wound and let the healing commence. It healed a bit better but about a year later I was intrigued by the fact that there was  still something there. I opened it again and squeezed and something the size of a grain of sand came out. It has since healed.
This year I have had a few similar bites. They start with a tiny raised or discolored area on my forearm. I don't think they itch but I scratch them, a day or two later a scab forms, a few weeks later the scab s still there and I get paranoid. I uncover the scab and there is a blood blister underneath. I start the process again and when one looks like it is about to heal, another one pops up.  
I do not take any drugs. I am aware and worried it could be skin damage from the sun but thought it could be a bug or plant as well.  Any ideas?

[chellybeans]

go to the dermatologist and ask for a skin exam. basal cell carcinoma can sometimes look like unhealing bumps. it is very easily treated if caught earlier.

also actinic keratosis can be scaly scabby spots of sun damage with a predisposition to turn into skin cancer. also very easily treated(liquid nitrogen)

basal cell carcinoma can look like a nodule or bump, squamous cell carcinoma is typically a scaly scabby lesion. both nedd medical intervention, and if it is neither, at least you'll be able to put the worries to rest.

good luck :)

[courly03]

I went to Costa Rica in November for 3 months. Since I've been back I have these bumps on my legs that wont heal. They still itch. I have about thirteen on my left leg, and 5 on my right, They are small bumps with a dark edge around them. I'm starting to freak out becuase I have been back for 5 months now and they still itch, and some have changed in size. Do you have any idea of what this could be?