Not wanting to play it down but it could be cramp set off by overuse with the 2 hard training sessions without sufficient recovery time. If you’ve been sitting in the same position for a while when travelling to your holiday it wouldn’t help things either.
When the muscle go into spasm they tighten up hard and if you’ve tried to stretch them off whilst in spasm you can do some damage. It may be you’ve made it worse by stretching before they had a chance to relax.
Very painful, hope it eases off soon, lay off the training sessions for a few days and go for a few walks to keep the legs moving.
Maybe a visit to a doctor for a proper diagnosis as well. 😉