Lumps on spine

[forelegs]

Whilst riding out today my horse started to headshake, something he has not done before, as if he was uncomfortable in some way. I walked home and when I untacked him I found three hard lumps along the spine under the saddle. There was no excess heat in them and they did yield to pressure when prodded. The horse did react by headshaking again when the lumps were prodded.
They started to go down by themselves after about 15 minutes, I then iced them for 10 minutes and they went down more but did not disappear. I made sure before riding that no part of the numnah was touching the spine and the saddle was newly fitted two weeks ago. The saddle was on for 45 minutes of walking, and there were no lumps at all when i tacked up.
Any suggestions as to what these lumps may be or how to proceed from here would be much appreciated!

 

[be positive]

It is likely that they are pressure sores from the new saddle, I would get the saddle fitter back to check it unless you have changed the numnah since the fitting which may be making the difference.
The headshaking is obviously related, one of mine had been written off by the vets as a headshaker, it proved to be caused by pressure from a badly fitting saddle, once he came to me I changed his saddle, had several physio sessions, built up his topline which meant another saddle, he went from a medium to extra wide in less than a year and the headshaking never came back.