Oh Maureen I am so sorry you are experiencing so many infections. I don't suffer in this way but I can appreciate how difficult this is for you. Its difficult sometimes avoiding people who may be infected with colds annd flu, its ironic that hospital and doc waiting rooms are not such a good place for us.
There are several things I do for myself, which I find help me. These are my own personal self help aids that I use.
I carry with me and use a throat spray when going into at risk places, like supermarket and doc surgeries etc, the throat sprays I use are, bee propolis and echinacea, the idea is that they kill any bacteria in the back of the throat. I use this immediately if someone coughs or sneezes, in the winter months I often use it before going into high risk places. You can also buy echinacea throat lozenges. I get these from the health food shop but I think you can get in Boots chemist too.
Another thing I use is the listerine total mouth wash and gargle, I use this when I have been in contact with coughs and sneezes etc. The first signs of a cold or sore throat I use this 3 times daily along with echinacea drops, or sambucol.
I try to eat with my meals each day is garlic, green root ginger and chilli. I believe these three food enhancers along with fresh herbs such as thyme, rosemary and peppermint, all help the respiratory and immune system.
Garlic is a natural anti-biotic too so even though it cannot work in the same way to treat a chest infection as prescribed anti biotics do, I believe eating garlic daily can help build the immune system to help prevent infection. Of course the recommended healthy eating, protein, fresh fruit and vegetables every day etc, diet plays an important part in our health and the bodies ability to help fight infectionn.
I am so sorry the medicines have damaged your immune system Maureen, I think this is why its so important we are aware of the foods that can help replenish some of the damage the medicines may cause.
I am wishihng that the infections become less frequent for you.
Take good care