Can anyone please help with this tree?

[Unforgettablefire]

I have a plum tree and it sank into the soil after I planted it. I've had it about six years.
It's been leaking sap so I've pruned it and researched diseases and it turns out the bark isn't meant to be covered with soil. So I have been scratching at the soil for days trying to find the flare and was delighted when I found it but I think it's a root as it doesn't go all the way round, and there's still bark way down into the ground no matter how far I go.
I don't know whether to leave this root exposed and carry on digging looking for the flare? I don't even remember if it had one.
I've also found what appears to be roots growing upwards.
My tree is sitting in a deep well with no sign of a flare I'm literally clueless please help!

Ideally you plant things at the depth they were in the pot, but if yours has been happy at the depth it was for 6 years then I would imagine that\s not the problem.

Do you have a photo of the sap/problem? It could be just an innocent leakage of sap, or from a bit of damage, or it could have canker.

This is what looks like it's growing upwards

Thank you for replying. I got some more photos it's not like this everywhere and I've cut loads of it off but wanted to save some plums I've lost loads and the tree is like a skeleton.
I could cry what the hell have I done.

Another pic as I could only add three.
My mind is frazzled.

Those brown knobbly bits in the first photo they don't look good at all, they leak sap but I've cut loads off it off I went and bought telescopic loppers to cut the top down it was so unhealthy looking.