Sounds like the same problem I had with my calves, and still have to some degree. They were ready to burst, and eventually within a few days of each other, they both tore.
I had various blood tests, all minerals and muscle enzymes were OK. The doctors could't fix it. Had fairly extensive physio to recover.
Anyway, after some extensive research on my part, I found that it comes down to a Magnesium deficiency (which cannot be seen in a blood test), not because I didn't take enough magnesium, but because I took too much calcium supplementation. I had surgery some time ago to repair my shoulders, and took extra calcium to help repair the bone injuries. I was also on antacid and proton pump inihibitors....all of which combined to blow my Calcium intake out of sight. I worked out my calcium /magnesium intake ratio was around 9:1. It should be something like 3:2.
The severe tightness is caused because the muscle fibres cannot relax. The magnesium in the cells is overwhelmed by the calcium, which over-excites the cells, and results in calves which twitch all day, and are under too much tension. In the gym i'm OK, but when I'm just walking around the get so tight and feel like they might tear again
I'm overcoming the problem by redressing the balance: cutting out calcium supplementation almost completely (other than a multi-mineral), gradually over-dosing on magnesium (it's not so easy because too much gives as a laxative). Its a slow process. It turns out that to fully replenish the muscle cell magnesium levels can take many months, even up to one year. Magnesium is easier to deplete than to absorb.
So check your electrolyte intake, but especially your calcium/magnesium balance. If you suspect that the balance is wrong, cut the calcium and increase the magnesium drastically.