Well without more information like how the piercing was done, what kind of jewellery was used, what were you using for cleaning etc. I can't tell you what the problem may be other than it sounds like a possible allegric reaction or an infection. If you could provide more detail I would be happy to help you out.
Tender and swollen spots on the head could be from scalp issues. If the hair follicles are irritated, this can also cause tender spots.
If your neck is swollen and under your ears are red and tender, you may have swollen glands. Swollen glands are a result of an enlargement of the lymph nodes.
Chlamydia does not cause swollen glands.
If your dog has an ear infection it definitely could cause his eyes to be swollen. Infections can travel if not treated.
A cold sore itself can cause swollen lymph nodes.
An unclean oral piercing could cause bad breath.
it could be infected go see a dr
You've had swollen and tender breasts for three months with very visible blue and red veins? Why have you not seen a doctor about it?
If its been swollen, discolored (red/purple), or itchy for more than 2-3 weeks. Or if the drainage from the piercing is a dark yellow/greenish color. It could just be irritated if its red and swollen. Go check with your piercer to be sure.
Hormone imbalances can definitely cause this, as can too much caffeine.
Firstly, you need to figure out why it is hurting, so have a look at it in a mirror. If it is swollen as well as hurting: if it is swollen it could be infected, so it is very important that you don't take the jewellery out as it could heal up and leave the infection trapped in your skin. What you should do is clean it with a mild salt water solution, if it doesn't improve after a week of doing this, go to your doctor for antibiotics and to get the jewellery removed safely. If it is not swollen: if your cartilage piercing is hurting but isn't swollen, it could just be that you've slept on it funny, that your bar is too tight, or it could just be very slightly swollen and sore. If there isn't obvious swelling and the pain has come on suddenly it usually helps to just take the jewellery out for as long as you can then put it back in (only if it's healed though! If it isn't healed just loosen the bar if possible and clean the piercing)
A large risk for any piercing, really, is that of infection. Also, due to placement, the piercing could easily get caught on something. If it is not un-caught, it could get ripped out. The placement could also cause it to be mroe painful or distracting.