It also could be boredom, bad diet, too much or too little exercise, lack of sleep, overexhaustion, underlying medical condition, or just a phase and so on.

These questions can't be answered by: me, yourself or a random stranger on the net.

Seriously, see a medical professional. I'm speaking from experience here.

A bad analogy (and I'm not being snarky) would be: "I've got a headache, have I got brain cancer?"