Okay. So, I think it's safe to say that you've probably used more Amphetamine than what would normally be appropriate for someone with your given tolerance and physiology. The thing about overdosing on Amphetamines is, there is a much larger "window" of non-lethality compared to say, Opioids, which are well known for the lethal dose being relatively close to the recreational dose. What you're experincing is common for high doses and I believe is related to vascoconstriction in general, as well as general symptoms of hypertension. These symptoms include a sensation of pressure in the body, difficulty passing urine etc.
Another thing about Amphetamines, is that you will typically go completely fucking crazy if you use way too much. This is known as Amphetamine Psychosis. I'm not even a major user, but I experienced pretty serious psychosis when I was 14 and took 200mg of Amphetamine in the form of Adderall (Dextro/Levo Amphetamine).
The simple fact is, in my opinion, the fact that you're talking coherently and are not hallucinating would imply that you're going to be fine. You just used too much. Try and remember ths for next time. If your Amphetamine was even of modest purity, an entire gram would have you in your backyard catching Komodo Dragons hiding in the trees with a swiffer wet jet. Just chill out and wait for it to pass. Drink lots of water. This will help you excrete the Amphetamine more quickly.
In addition, if you're ever looking to speed the excretion of your Amphetamine, take advantage of the drug(s)' unique pharmacokinetics. Amphetamine, as well as Cathinones as far as I'm aware are heavily influenced by the Ph of the users' urine. Essentially, a more alkaline setting means the Amphetamine is going to be absorbed at a higher rate. A more basic or, acidic urine will lead to more of the Amphetamine being excreted as an essentially unchanged product.
This is all off the top of my head, but it's basically like this: Between 25% and 50% of Amphetamine has the potential to be excreted as an unchanged product in the urine. The more Alkaline urine means as little as 25% will be excreted in this way, whereas the basic environment means up to 50% of the drug will be exreted unchanged. This is a rather significant variability. If you drank a true tweaker's urine, you would likely get so fucked you would go psychotic.
This is also something to consider simply for the fact that you seem to be relatively unfamiliar with Amphetamines. Be aware that a similar dose can have significantly different results from time to time based upon this whole Ph thing.
