How should chronic dermatitis caused by autoimmune diseases be managed?

It seems that my husband's health has changed since he had surgery for cellulitis three years ago.

In the past, I didn't experience this, but now when I get a skin wound, it doesn't heal and instead oozes and gradually spreads. When I went to a local clinic, they said it might be related to skin immunity and mentioned the possibility of an autoimmune disease. It's very unfortunate to see that even minor wounds always ooze and don't heal. The doctor said it seems like my constitution has changed. They told me I have no choice but to avoid injuries at all costs. I'm not sure if it's due to carelessness or something else, but I keep getting injured just about every time, so I think I visit the dermatologist once every 1-2 months. The doctor also said they don't know the details well and recommended going to a larger hospital. Does anyone know about these symptoms? I think I need to improve my constitution, but honestly, even trying chlorella types didn't really help—it's mostly only useful for allergy reactions, and I didn't see much improvement. I want to try improving through diet, but I don't know where to start.ㅠ