Thank you for your query at DoctorSpring.com.
I understand your concern.
In my opinion, your symptoms of numbness in the right leg and the heel pain are significant. Lower backache is mostly a mechanical pain which will improve with back strengthening exercises. The other symptoms are general, non-specific and nothing to worry about. They are most likely to be stress induced.
The numbness and heel pain, like your GP said, are likely due to nerve inflammation. The blood tests your GP has ordered may be routinely performed tests like a complete blood count, markers of inflammation like ESR, blood sugar levels. These blood tests are done as a routine and the markers to check for inflammation. Blood sugar levels are tested to check for Diabetes which can be a common cause for nerve inflammation. Once the results are back, Diabetes is ruled out, he may prescribe medications for nerve inflammation and pain. So in short, you do not have to worry about any serious illness. Please relax.
I suggest that you start off with mild back strengthening exercises to take care of the backache. You should also engage in activities like meditation, or your favourite hobby to de-stress yourself. Mild aerobic exercise not only brings down stress levels but also gets rid of fatigue. So please engage in it daily.
I hope this was helpful.
Feel free to ask further queries.