Husband can’t pick up because higher ups

So, I don’t know what would be my rights or ways of help from my end to get this prejudice and discrimination against my husband.

My husband is an E4 and is eligible for promotion HOWEVER a few sergeants are making it impossible for my husband to take the next step. They are constantly singling him out to do random, degrading tasks.

My husband is not a person of color (although I am), but the sergeants are Asian and Hispanic. Regardless is still discrimination BUT because they are higher ups usually Army brushes it under the rug if lower enlisted speak up for any form of discrimination or harassment things do escalate.

My husband is going down a dangerous path (mentally and emotionally) and I don’t know what to do. He feels as though if he were to seek help or guidance it will come back to bite him.

I’ll be dammed if I lose my husband because of two assholes.