Hi Leth,
I felt that this is a hams strain at upper musculotendinous junction, where it is very susceptible and common to tear.It is better to examined by a Physio hence you need to prevent recurrent hams strains.
If the pain is still going on I suggest to keep ice on the area where you feel pain for 2minutes and hot fermentation 2minutes alternatively; for 20 mins (keep care on ice burns and all). Do gentle stretches and after pain subsides start strengthen exs for hams.It is better to do these exs under the supervision of a physio.
Hope ur recovery soon!
isanka