Shoulder injury from swimming??

A couple of weeks ago I noticed my shoulder was feeling weird after a day of training all 3 disciplines (swim was first) and snow shoveling.  I was raging within a mentor group and someone wondered if I had been over training the swim.  I had not considered this until she mentioned it but it has me guessing and wanting to put it out there to more people.

My swims have been intentionally getting longer since November and I am wondering if I have outstretched the boundaries of proper training increases?  It doesn't seem like it to me but what does everyone think?

First of all the injury is to my left deltoid, from the mid-line at the top of the shoulder to where it meets the tricep/bicep then it radiates back to include the rear delt to a much lesser degree.  I get a burning sensation at the middle of the delt from certain movements but most of the time it doesn't seem to bother me.  I have taken a week away from swimming but work didn't help me a ton and the additional snow we got in this region kept me shoveling and aggravating it some.

Here are my weekly swim totals since
November: 4000, 4800, 5550   - December: 5600, 6000, 7250, 9700 (3 swims this week)   - January: 5350, 7600, 4000, 7750 and the last swim week I dropped one swim and went very easy at 2700 yards.  I did not swim at all last week and plan one more week off before getting back in the water.

Am I way out of line for 2 swims a week?  I had no problems before the swim/run/bike/snow shoveling day.