Decided to use the treadmill again since I'm trying to gauge my distance.
Put the speed up slightly from 6 to 6.5 and 10mins in started to get little electric shocks from inside top of knee. Reduced back to 6 and carried on, no problem. 20mins in increased to only 6.2 and the little shocks started again. How very strange. Reduced speed and ran for 30 mins to cover 3km.
Slightly concerned there's an injury brewing. Any thoughts or suggestions very much appreciated.