It is probably because you are under a lot of stress. When you are under stress, you can have lots of dreams because your mind is trying to process what is bothering you. As a result, you may not be getting a whole lot of deep sleep. That can cause you to feel tired when you wake up.
You might also want to check with your doctor to be sure you don't have sleep apnea. Sleep apnea can cause you to wake up frequently in the night (you may not be aware of this) resulting in less deep sleep. Your brain tries to catch up by having many dreams (REM sleep) when you do sleep. As a result, you can wake up feeling tired, like you didn't sleep at all.
Finally, some medications can cause sleep disturbance. Talk to your doctor about the side effects of your medication. You may need to change medications or reduce the amount you take.
You can try warm milk before bed to help. Also, try relaxation exercises when you get into bed. Listen to soothing music, read or do other quiet activities in the hours before you go to sleep. If you feel none of these things work, try asking your doctor for a mild sleep aid until you feel you have gotten back to regular sleep patterns.
You would need to check with your doctor. Everyone reacts differently to medications so it's hard to tell if they would affect you like that. Your doctor has your medical history and would know that information better.
There is no way to tell. It could be that you need a medication change or that there is something bothering you that you are not aware of yet. Or it could be the weather. Sometimes it affects you more than you realized. And it could just be a few off days. Everyone has them from time to time. I would give it a few more days and if you do not feel better, call your doctor. You may need to see him.
Yes, I do. I recognized your name from before.
We do need to close this question with a rating and start a new one.