getting started with the medic is BRUTAL. the starting LMG without any site is just awful. I play on HC servers, I may have to go vanilla until I rack up enough points for an optical zoom and some better guns.
I didn't think it was too bad.
You just really have to play a true support role for the first few unlocks before you can start to do your own thing. Find a player or squad that you like what they're doing, and just stick to them.
The medic machine guns are actually built for excellent support in that their extremely large ammo capacities means you can maintain a base of fire while your teammates might have to reload.
Just stay behind them and spray bullets at targets they're going for as well, you might 'steal' a few kills or at least get assists (make sure you're always spotting with 'Q' for extra points!).
If you're running around with anyone else that is also a medic, jump on any opportunity to pick up their kit should they die and start whoring the medkits (tons of points for healing) and defibs (50 points for regular revive, 80 points for squad).
And whenever you are using some level up medic kit (whether stolen or you've finally earned the medkit and defib on your own), just try and stay back from the action, try to be the last one to die instead of in the front of the group. True support medics tht throw medkits on injured teammates and defib dead players score
a lot more points than combat medics.
And if you really cannot stand to use the vanilla PKM, you could always try using an All Kit weapon such as a shotgun or M14/G3/Thompson