My probiotic strategy

I am a 18 year old male who has been suffering through gastrointestinal problems his whole life. I keep telling my dad it's different things. I first I thought I had parasites because I was seeing white things in my stool Candida). He thinks I'm a hypochondriac and I don't know what do anymore. The only way I can have a normal bowel movement is if I take magnesium citrate.

My symptoms include:

-Hard Round Stools entire life.(Don't blame on diet, my brother has fine bowel movements and he eats worse than me)

-Chronically bloated (Got someone better after magnesium, but only works half the time)

-Chronic Candida overgrowth.(Oral thrush and seeing it in my bowel movements.)

-Currently underweight and lacking in behind in puberty compared to my peers.(My bones stick out quite a bit, my body looks gross.

-Brain fog and horrible with direction.

Can anyone help me out here? Should I just go see a gastroenterologist? I'm just afraid we will spend money we don't have on a diagnosis like "IBS-C" or he won't even know what Candida is.

My probiotic strategy is to make a solution of 1 Colostrum capsule, 1 Bacillus Coagulans capsule, and 1-2 teaspoons of L-Glutamine in milk every night. I will drink the solution on an empty stomach when I first wake up. Nothing has worked for me and I have doubts about this too.