Thanks for writing to us,Pravachol
can lead to muscle pain
but back pain
may be occuring due to different reasons.
As per your symptoms probability of space occupying lesion in your brain .
Yes MRI brain will confirm diagnosis I will advise to do some blood test
which will aslo guide regarding nature of lesion.
If needed after MRI ,PET SCAN CAN BE DONE.
Yes you need to hurry to do MRI.
I hope that I have answered your query. Let me know if I can help you further. Take care