I just had my SP1 go down in first week of new season... 38 day injury. My medical is set at 11mil. My choices for DL are 15 or 60. 60 would keep him out of action for 22 more days than needed. Can i do multiple 15 day DL's ? I never tried it. Fir example 3 consecutive 15 day DL stints so i only lose him for 45 days instead of 60. Again.. injury is 38 days and he lost a few points in some key skills

You can put him on the 15 day DL and leave him there for the 38 days.

You would not be able to remove him from the DL until he was healthy even if you wanted to.

I think I've actually done that before. Anyway you could put him on the 15 and try it. Worst case scenario is you can't remove and add again, so what? Better than putting him on the 60 and losing him for the extra 22 days.

As tecwrg said, you can put a guy on the 15 day DL and leave him there indefinitely.  He'll be eligible to come off when he's healthy and at least 15 days have passed.  The only reason to use the 60 day DL is that it frees up a 40 man roster spot and injury recovery seems to work better--in this case though, just 15 day DL him and you'll be able to leave him there until the day he is healthy, then you can immediately add him back to the roster.

You can remove a player from the 15-day DL after 15 days, healthy or not; I've accidentally done it.  But why would you ever want to remove an injured player from the DL?  Just do what tec said, and remove him from the 15 when healthy.