no ones going to tell you for sure what has caused the bad reaction; it could be a number of things (combined).
my first assumption would be some kind of containment left after the cook, an impurity. or it could have been something put in to make the bag weigh up, or it could be...etc. you get my point.
after a few weeks break, smoking a point of meth could have been an overdose - depending whether the shit you get was better than the usual or not - and you've had an adverse reaction. whatever it was i, when still using meth, have experienced piercing migraines and been on the verge of projectile vomiting when we received a better batch of gear than usual and shot more than we would usually IV.
how much water have you had to drink? you can over-hydrate yourself which can exacerbate some of the negative symptoms you're going through. be sure to keep hydrated but not so much that you drown yourself. try and munch on some light fruit such as grapes, apples, oranges and bananas for example - light foods with good nutritional value and reasonably easy to stomach whole tweaking
i would go and seek an ER, be honest with them about what happened and they'll hopefully give you the best treatment they're able to - better than an internet forum.
i hope you're ok and please let us know when you're better.