It sounds to me that you really need to build your strength up again. You definetely should not go hungry so eating enough is important. If you have reactions to buckwheat and teff you might want to try rotating the grains so that you don’t have the same grains every day and give your digestive system a break in between. For example having teff one day, buckwheat the other, then try coconut flour bread the next etc. This might increase your toleration and then you’d have more options for foods.
Also eating enough to bind the waste together and to keep things moving on is very important in terms of general detoxing. We need to eliminate the waste and not just let it sit in the colon. Eating lots of vegetables like broccoli, cauliflower etc might help you get the binding bulk you need. But you may need to eat a lot!
It could be that your lungs are doing their best to detox now. Though I haven’t gone through what you are going through I can only share what I do when my seasonal allergies are at their worst and my lungs are kind og congested. I do steam breathing with a drop of eucalyptus oil; it calms my lungs and clears my sinuses somewhat. I also use the neti pot to cleanse the nostrils with salt water. For throat problems I gurggle with salt water. Oil pulling (swishing coconut oil in your mouth for 20 mins in the morning) is also useful for getting mucus out. After oil pulling I use a tongue scraper to clean the tongue.
Some thoughts about iron: it is possible that if your stomach is feeling especially vulnerable now eating red meat or taking iron supplements may be too harsh on it. But at the same time getting those iron leves up would make you feel a lot stronger. Some supplements are easier on the stomach than others (I’m taking a Norwegian brand so no point in recommending it as you probably would not be able to get it). Though I’m thinking that you might also be deficient in vitamin B’s – did you have this checked? (another result of strong antibiotic use, and another cause for feeling weak). Another thing to consider is that if your digestion is weak your ability to absorb iron could be lessened. I went for years being anemic while the supplements I was eating just lieratlly washed through me with no effect. Finally I changed doctor and was given iron injections straight to the muscle. All it took was 5 shots to get me up to normal level. I know it sounds kind of drastic but if you are struggling to get your iron up this might another option be worth considering?