help with fitness trackers -

Hello! I have a questions about fitness trackers. I use the one on my Samsung, SHealth, to track my steps. I have downloaded the MyFitnessPlan app recommended by the clinic. But I am hoping to find a walk interval trainer that will record training for a 5k? I am not ever going to run because of my knees, (the osteo is bad) but I really like the SunRun interval training for walking - I'd like to have a record of it and to track my progress. Everything i have found is walk/run interval trackers. Any ideas for android, walking apps would love to hear!

Also: I can't find any trackers that record swimming. This is annoying as swimming is my primary go  toexercise now. Any one else swim? It would be straightforward record keeping but no place in MFP or SHealth for swimming...

thanks all!

Tamara