Had microneedling done four days ago on my thighs arms still burning and stinging???? Is it infected? (photo)

It is difficult to tell from your picture exactly what is going on.  However, it is somewhat unusual to have significant burning and stinging four days after microneedling, so I recommend returning to the provider who did the treatment and letting the assess your legs and arms.  In the meantime, be sure that you are keeping those areas very well protected from the sun and that you are using only soaps and lotions that your provider has OK'd after the treatment.Best of luck to you.