Should I have a further assessment for my whiplash claim?

Hi there. Someone went into the back of my car and I suffered whiplash. The GP I saw as part of my claim predicted I would recover in four months and said that no Physio was necessary. During the four month period the pain got worse and my solicitor told me I would need to seek NHS treatment and after seeing my own GP I was referred for a course of NHS Physio.
I have now passed the four month period and my solicitors say I can settle my claim if I am symptom free or can be referred for Orthopedic assessment if I am still suffering. However they have stated that if the Orthopedic specialist does not find enough evidence that I am still in pain or decides to attribute my symptoms to an underlying condition that I will be liable for the cost of this referral which is Â?700 and will be deducted from my compensation.
My pain now is only very minor, it is mainly just a little restriction when I turn my head to one side and I get pain and tingling if driving long distances or if standing or sitting for long periods of time. I am not sure what to do for the best, on one hand I still have some minor symptoms but on the other hand they are only minor and the specialist could decide there isn't enough evidence which would leave me with a big bill to pay.
Any advice would be gratefully received.