I'm so sorry this is happening! Let me begin by saying that I'm not a roach expert by any means. Any ideas I have are based on reading I've done for the benefit of my dogs, cats, mouse or other critters. I'm still learning about roaches and I appreciate any corrections from the roach community.
I had a piece of toast with coconut oil the other day. I put a small piece in with the roaches who loved it. Unrefined organic coconut oil has, among other benefits, antifungal and antibacterial properties. I wonder, if your roaches are still eating, if this may be helpful. I also use very high quality essential oils. Many essential oils have the same properties as the coconut oil but are more concentrated. If you have access to therapeutic quality oils (safe for human consumption), I'd choose citrus oils. 1 or 2 drops in a 4 oz glass spray bottle filled with distilled or spring water could be used for misting or your could wash any produce you give them in a bowl of water with 1 or 2 drops added. With essential oils it is better to start with very little as you can always add more if needed. Too much right away may not be helpful.
I hope to hear your roaches are improving!