Major mood swings after a miscarriage are absolutely normal. You are going throw some serious hormonal changes, plus the loss of a pregnancy (even one that is unplanned) is naturally going to have some emotional repurcussions.
I remember thinking after my miscarriage that I might have PPD. I did some research on the Internet (not the best source of medical information) and from what I read it is possible to have PPD after a miscarriage. I did not have PPD, as it turned out. I was just devastated and hormonal.
PPD or not, take some basic precautions. Get out of the house every day where possible. Take your son on walks, be around people. Try to get physically active (if the doctor is ok with basic walking around). These should help.
If you are having any really concerning problems (inability to care for your son, feelings of worthlessness, thoughts of harming yourself or others) call your doctor immediately. If not, you can wait a few days to see if it calms down.
I know after my miscarriage it took more than 10 days to get my emotional footing back.
Try to take care of yourself at this difficult time!