Ditto on the MRI, though it should include head and cervical spine. It is possible that you are experiencing the early stages of a demyelinating disease (such as MS) or a systemic auto-immune syndrome (like Lupus or rheumatoid arthritis). It may also be something as innocuous as a minor viral infection, but in any case you should see a doctor as soon as practical. Good luck, and best wishes.
I must advise you that I am not a doctor. Hopefully someone with more medical training will log on soon to help you. Again, take care!
I would get a cervical MRI as damage to your neck such as a herniated disk or something else can cause your left pinky and ring finger to go number. Have you fallen, lifted anything heavy or been in a car accident in recent years? Also, neck problems would cause headaches in the back of the head as well as neck. And you can get referred pain to your chest. If your neuroforamina is pinched you could get symptoms down into your hands as you describe. Have you fallen or had an accident?This can all come from arthritis, bad disk, or other spinal/neck problem. Perhaps you need physical therapy because you hurt yourself caring for your children and did not realize it. You may have pinched a nerve...and between two kids and pain you could get emotional problems such as depression. And it could affect what little sleep you have time to get. This would be my immediate guess.
Otherwise, since you feel heavy on the left side, are tired, have chest pain and severe headaches I wonder if there is a history of migraines or circulatory/heart or immune problems. Also, infections which affect your nervous system can cause similar symptoms. Have you been sick or have any rashes or fevers? These problems can sometimes cause mood changes as well.
You are young and have two children. Again, too much pain can eventually lead to depression. I would definitely see a doctor because you are probably going to need treatment to get better. Hope this helps. Best of luck to you and your family!