All the above are true -after I got a shot day before, still I could not sleep - with the support of right arm (where I got the shot) and a palpable heat along with slight swelling in the area of injection.
I had the same thing happen to me when I got my tetanus shot few years ago. Later on I read it happens because tetanus shot is actually a vaccine and like all other vaccines it contains not active tetanus toxins that cause the potentially deadly disease when you don't get the shot in time.
The reaction you are experiencing is just your immune system reacting to these so it could learn to fight the disease on it's own. You can put a cold pack for 15-20 minutes on the place of the shot to dull the pain - it helps, and all and all - all these symptoms do go away in a day or two.
Thanks for your advice. Now as u say, pain has reduced immensely, and also the heat around injected muscle.