What Are The Side Effects Of Seretide?

I have ben an asthma sufferer for 63 long years and live in the United Kingdom. I currently take the asthma drug SERETIDE 250 EVOHALER free inch 25 micrograms+ 250 micrograms/actuation. Mitte (10 120 dose inhaler with counter.I have read that one possible side effect of SERETIDE is that it can cause low blood potassium levels. I have suddenly stopped taking it for the past 5 days and I now am actually experiencing total exhaustion/lethargy,etc. Would suddenly stop taking SERETIDE cause these symptoms for me personally? I DO NOT WANT to rely on corticoidsteroid drug category any more in the future and will only rely on my quick acting Salbutamol and Atrovent inhalers only as I always used to do BEFORE drugs such as SERETIDE came onto the market. I want to try very hard to refrain from relying on steroid drugs for asthma as side effects are quite nasty in certain respects. Is ir POSSIBLE doctor for asthmatics to be effectively treated on other types of medicines apart from Corticoidsteroid drugs ???? Thank you.