I get this a lot with my running.

My tips would be, make sure you’ve had enough fluids, magnesium spray, raise legs if possible? And my sure fire winner, rolling your calves. A foam roller if you have one or in an emergency a tin of bins or similar, wine bottle, or tennis ball which is far more portable.

I’ve also found icing my calves help too but you don’t always have an ice pack just laying around in your handbag!