Hey Rose, I had a murmur picked up by my ob too. I went for an ECG the next day and got the all clear, the sonographer told me she could see "nothing scary", I'll discuss the results with my ob next week though.

The ECG itself takes ages and is a bit uncomfortable when they're poking around your breast (I have melons at the moment so if you are smaller breasted I don't think it would be such an issue) I had mine done at about 10 weeks too so they were still pretty sore. You might get uncomfortable too because you have to lay still for so long and at 26 weeks I'm sure you have quite a bump happening.

I'm sure it's nothing to be concerned about, I was also told they are quite common in prg women due to the increased output of the heart. Good luck!