PIP not sure what to do

hey im new to this website and thought i would come and ask for some help or even some guidance.
i have phoned the DWP to make a claim for PIP.
ever since going the doctors with chronic pain and stiffness in my hip and lower back.
the doctor said it would be one of 2 things 1) osteoarthritis 2)fibromyalgia.
but since she can't rule out these she has referred me to see a specialist and physiotherapy.
at the moment i'm still waiting for a referral.

but since i asked the dwp for a form to fill in and reading these guides it says for evidence to show any letters or appointments for specialists etc. at the moment i don't have any letters because im waiting to hear.
so what do i do? continue to fill in the form and get rejected with no supporting evidence.
or wait till i have a letter from the specialist before i fill in the form?

also because my partner is constantly helping me and with no other aids available until i see a specialist will this count against me.
i'm back and forth the doctors pretty much 3 times a week with constant agony pain and stiffness its to the point where it is unbearable.
i just don't know what to do with this pip form at all

and then to top it all off the DWP have lost my sons DLA claim and we are on the phone throughout the day trying to see if they can find it. and that's adding to more stress please help if you can would really appreciate it.

hi thanks for the reply i have this now for about 5 years and i know my gran had suffered with it when she was my age (26) and had to have a full hip replacement in both hips and stilll suffers pain and stiffness. so im not sure if this runs in the family.
i have spoken to my doctor and all she could say was because she is just a general GP i would have to be referred to a specialist for further tests.

but pretty much all i got from my gp was that all she can do is prescribe pain killers until the request comes through