MCL and slight lower back pain

The titles says it, and its not overwhelming. As I write this I actually am reminded that this pain has only come about in the past few rides, of which are longer than usual. The bike is my only mode of transportation, and does a great job at it. daily i commute minimum of 18 miles. The past week i have been commuting in excess of 32 miles a day, along with walking and standing immediately after riding. I haven't really taken the time to observe any difference's in posture or seat height/position, so perhaps this is a contributing factor. This pain came about briefly maybe 3 months ago, and faded away slowly. I can recal riding earlier today, and briefly feeling that my ankles were not "lined" up properly with the bones in my legs. I had to put more effort into focusing than normal. this slight hindrance could be from the added mileage, especially within the past two days. Any insight is appreciated. Cheers.