i am starting to work out now and i am 17 years old.

so, everytime i lift alot, my right elbow starts to hurt when its bent.
there is a lot of pain when i push the weight (benchpress), im not even sure it is pain, it just feels really weird and i cant lift the weight as easily.
i have also been drinking alot of milk lately.
im not sure if its because i have had to much milk?
or should i take some d3 pills?
the pain is also extremely minor and basically unnoticeable once i just stop with the weights.

any ideas as to what this is or what i can do?

Thanks!