Hi
@PTracey and welcome to the planet.
lethargic and aching arms is a new one on me.
the first 2 weeks your body goes through the detox process which clears all the shite out of your lungs. some well known side effects are having too much nic which is headache and feeling sick. vape does dehydrate the body and plenty of water drinking is a must.
as your using 20mg im guessing they are nic salts which are a lot smoother than normal nicotine based juices and give you a nic hit much quicker than normal freebase nicotine..
it might be worth trying some standard flavours with freebase nic in 18mg, 12 mg and 6mg to see if these have the same effect. also some people can be allergic to normally the pg. its just a trial and error process to see if you dont get on with certain juice or their content.
what kit did you buy and which make of juice are you using as there is a lot of shite being sold out there.
also what flavours do you like so we can point you to some decent suppliers.
this link may come in handy for future reference as all recommended by members
POTV Vendors & Recommended E Liquid Suppliers