Dry skin is a sideeffect of any amfetamine use – the twitches can also happen with heavier use. I do not think they are dangerous/lifethreatening and should go away with less use or quitting; but if you are concerned then see a proper health professional if possible..
Meth is not common here in UK but I have been using amfetamine-type stims for nearly 30 years without major ill effects; and regularly ride a bicycle 30km to work and back. If I overdo things/do not get enough sleep then I get various aches and pains, but that would also be normal for someone who is now in their 40s anyway!
