Whats wrong with my babies???

Hey everyone!!!

This is my first grow and everything was going good! Both are in the vegetative state and were doing well but lately i've been having issues and I think it might be a Nitrogen deficiency. But I just wanted to make sure just incase! Thank you for your help! I have two plants hence the two different photos!

http://tinypic.com/r/6tmww9/5 *1st plant

http://tinypic.com/r/24kwkxt/5 * 2nd plant

Looks like yellowing? If you start to see this more and if there apoears to be lil yellow dots look under the leaf there might me spider mites eatin away at your THC. Buy ladybugs they eat little critters and eggs