Are both sentences OK?
All over my body is covered in mosquito bites.
Do you have an address or telephone number where I might reach them?

Question

Answer

Another way of saying it is:
My whole body is covered in mosquito bites!
Do you have a telephone number or an address where I can reach them? (can is more natural than might)

Answer

I would remove the word 'over' from the first sentence.
Also I would rephrase the second sentence in the next way:
Do you have an address or telephone number to reach them?