Is chest pain a caffeine withdrawal symptom?
If you have stopped taking in so much caffeine and are now experiencing chest pain, than it is not withdrawl. Usually you develop chest pain when you are taking in the caffeine, not once you have stopped. Do you have any other symptoms with your chest pain? Racing heart? Nausea? Sweating? Any of these could be a serious problem. Try to relax and see what happens. If the chest pain does not subside I would see your doctor.
Does hydrocodone make your heart beat faster?
Not many people report tachycardia (rapid heart rate) with hydrocodone--only 1.12% of hydrocodone users in this study: http://www.ehealthme.com/ds/acetaminophe... Which doesn't mean that *you* are not having that side effect. Hydrocodone may be increasing your anxiety, and anxiety certainly can cause your heart rate to speed up. Also note that what you consider to be your heart rate speeding up may be something a little different: it may be palpitations which may be thought of as awareness of your heart thumping in your chest. Your heart rate may not be actually speeding up; you may just be more aware of your heartbeat. If you actually count your heartbeats per minute before and after taking hydrocodone, does the count really increase even if you're sitting quietly? If not you may be having palpitations rather than tachycardia. In this study: http://www.ehealthme.com/ds/hydrocodone+... 2.34% of patients taking hydrocodone reported palpitations… still pretty low, but some people do have this. And again, anxiety and palpitations can go together. Neither tachycardia or palpitations is dangerous in this context, although you might want to mention them to your doctor the next time you visit, but if the side effect significantly bothers you, you would be very justified in deciding that hydrocodone was not worth it to you.
What is the best kind of synthetic marijuana?
None, it's all crap. I tried some called 'Black Mamba' once. It didn't even produce the same effect as real weed. It made my heart race and made me very paranoid, and gave me frightening chest pains. I almost called 911 because I thought I was having a heart attack. I do not recommend it at all. I'd rather get busted with real weed than smoke that crap.