Short on breath and high puls

LilBarbieFeet
Hi everyone. Im in my 24w and since my second trimester started Im having trouble breathing getting short on breath and all of the sudden high puls in the range of 120-130 in laying or sitting possition. 
Its not all day everyday. It happens like on 2 or 3 days a week and not constantly, holds on for like 10-15min and goes away. Does anybody have same problems?