Can malnutrition be causing my depression?

So I recently went on medication for OCD and depression about 5 months ago and I was doing pretty well up until about a week ago when my depression started to come back. I thought I might just need a dosage increase but I'm almost at the highest dose so I don't think that's the case. Lately I've been thinking it might be malnutrition because I haven't been eating that much over the past couple weeks because I'm too broke to go grocery shopping. I've pretty much been living on eggs and peanut butter over the last 2-3 weeks. I work at jimmy johns and I treat myself to a sandwich every now and then which is usually my only real meal during the week. Other than that it's literally 2 hard boiled eggs and peanhts/peanut butter when I'm at home. I've just been feeling very depressed and tired lately and I'm wondering if this might be why.