Internal injury to back of knee/thigh

[Eaumyword]

Hi all - would appreciate thoughts on this please?
DH was running 12 days ago and suddenly pulled up with an intense pain to the back of his knee/thigh area at the back. No snapping or popping sound.
Instead of stopping and sensibly icing/elevating/seeking medical advice, the silly arse tried to continue running - yes, I know 🙄
He didn't bang into anything and nothing hit him, so this seems to be an internal injury.
Heavy bruising appeared the next day and 12 days on, seems worse (the darker bruising pic was today.)
Any thoughts on what it is and how serious it might be please?

I can't tell how high up this is on his leg but this is what the back of my thigh looked like when I tore my hamstring

Thanks @OReillyTheOneEyedTelescope for replying. TBH, that's what I thought it is, a torn hamstring.
The bruising is just fractionally above the back of the knee, where the crease/bendy bit is where your leg bends at the knee (sorry, a bit wordy there!)
There is no heat/swelling/lumpy bits - just awful purple bruising.
Does it heal eventually on it's own?
I'll have a good google of torn hamstrings now!

I would recommend physio. I didn't go and then I tore it again! Then I went to physio and it healed properly! You have to be really careful as it could be a partial tear that then tears the whole way through and that can be more serious so it's better to go to the physio and get it checked out.

I did exactly what your husband did too and thought it wasn't serious and then carried on running. Then didn't go to physio. I ended up on crutches for 6 weeks. Maybe tell him that to persuade him to go!

I was going to suggest hamstring too and a sports physio!

Thank you both so much, really useful to know. I will pass it all on to him and hopefully all will be ok in time 👍