I have back pain in at the bottom of my back for about 3 years now and i have a lump on my knee and my dad have ms i have about 75% of the symptoms.?

75% is not enough: Need a spinal tap and examination to put your mind at ease!

See a neurologist,: As it is hard to tell what you may really have. Ms is not a disease of true heredity, but one of susceptibility, and with your dad's issues, your risk is but 1-2%. Not sure what the "75%" truly means, and perhaps your back pain is secondary to coccydynia, but a visit to a neurologist might reassure you quite nicely.