When i contract my calf muscles, i feel tingling sensation in my both feet all the time. no cramps. been to physio, no hernia or anything serious.

Neuro: Have you seen neurology? Just a thought since the tingling sensation seems to be the main issue. They may be able to direct you to neurophysiology who conduct electromyography and nerve conduction tests (unless you've already had that done?) to see if there is an abnormality in the nerves that run through/by your calf muscles. Thinking out loud.

Paresthesiae: By forcefully contracting your calf muscles, you may be compressing nerves leading into both feet causing temporary parasthesiae(tingling,pins and needles). If such symptoms occurred without pinching or impingement,then a peripheral neuropathy would be suspected.A physician could check the status of your nervous system and circulation of your lower extremities if necessary.