Hi, thanks for posting your query.
You have a painful bony lump on the inside of your left knee for which you have been advised MRI
scan by your doctor, then well I feel it should be done.
It could be tendenitis, bursitis
Even if it costs a lot of money and turns out to be nothing it is worth getting it diagnosed rather than repenting later on if the condition aggravates.
Hope you understand my point.
All the best.