Where would I be able to get a reliable testing?

My mum keeps telling me dont waste your money its all in your head with me worrying too much because she has some fillings and is fine and its only if your allergic. They dont understand how my concentration levels have shot and how depressed and anxious I have been and not knowing why it happenned or what made me worry so much about things in the first place.

Im in Birmingham UK and looking for a reliable place to get a good test done for mercury poisoning. Doctors dont believe in Candida either which is weird and makes me understand the pain mercury and candida sufferers go through. I just dont understand why they ignore it?

Im going to buy Algin tomorrow and selenium + Vitamin E and C and see if they help improve some of my symptoms.
Rhodiola and EPA fish oil and Evening Primrose seem to help some of my symptoms of inhibility to relax but I always have my concentration problems so I believe its definitly linked with mercury or food intolerances.