A very helpful history.
It is unlikely to be a DVT.....very unlikely.
If you are on holiday in warmer, hotter climes, then i must question whether you are drinking enough fluid. ...is your urine concentrated...if it is, then make sure that you drink more water until it becomes straw coloured.
Just wondered what other medications you are taking and what is your current medical history.
It does sound like a muscle strain and should be treated on that basis...ibuprofen and rest.
Give it another 24 hours to monitor the situation.