What causes transient and single little spot tingling under left foot without any other symptoms? one day i feel, one day i don't. 30, male.

Certainly: Nothing particularly serious. Make sure there is nothing in your shoe.

Intermittent: You could have minor nerve intermittent compression affecting aural or posterior tibial nerve, both at ankle and perhaps dependent upon foot posture. Alternatively, might be an issue with blood vessel flow, but far less likely. A podiatrist might check foot and ankle positions and assist with preventative interventions.