During my vigina gets lubricated but in a very watery consistency why has this started happening?

i was with my ex boyfriend for 3 yrs and the was fine but near the end of the relationship during my Virgina would get lubricated but in a very watery consistency (not from an ). since we split up i have had other partners and its been the same. I've gone to a gum clinic and i was clear of everything i was tested for. i don't know if i should worry! how do i stop this happening?