VNS sensitivity can it work on real low freguency for some?

Well I know I have a pretty sensitive body and it will tell me when something is working or not. So I have intractable epilepsy, I do not have many more options and so had the VNS put in. After the surgery I had left vocal paralysis for 8 weeks so I was not happy. So I chose not to turn it on for 5 months. Two weeks ago I had to acknowledge thaty my seizures were still not getting better, so agreed to turn on the VNS on lowest possible. I did okay after afew days. This past week I had the freguencty turned up slightly and had a bad week of all kinds of reactions, tightness of chest, difficulty breathing, coughing etc. Fortunately my Epitomologist has a good understanding how sensitive I am so I was back in this AM and had it turned way down and wow I feel tons . I am now having doubt as to whether I will be able to have it turned up ever as my body can not handle the higher frguency and so I have major doubt about it . So my guestion is Are there any people out there who have a vns and find thier setting has to be real real low settings and low frequency and if so does it help them? Have others find it usefulat this level? look forward to hear others personal experience and thoughts.