I guess your coil could be getting clogged if you have high VG liquid in there. But you must have gotten juice from your friend too? Look at it (or ask him) and see if you can see percentages of VG and PG. You may need to up the PG. It could be the device, IDK. Hard to tell, if you got it from a friend. It could be the device, or the eliquid, but for whatever reason your coils and your mod aren't playing well. Etc..
Good luck and welcome.
Anna