I started to see small itchy pimples on my hands. now, they are starting to show up on the whole body. what can be a reason of that? what should i do?

Scabies?: It might be scabies, esp if it's in the webbing between fingers. The bumps look like the pic, and sometimes you will see small red lines or burrows. Permethrin is the tx of choice. However, hand-foot-mouth and contact dermatitis are also possibilities. See a doctor for a more definitive dx. Meanwhile antihistamines like benadryl (diphenhydramine) or Zyrtec will help w the itching. Good luck!