I never suggest medics to engage combat aggressively, since your wounded teammates can be healed by you, but no one is going to heal you when you take a punch. And medics are less combat effective than others, so after your 401 purchase, give money to other frontline perks, then back-row perks. If you still have extra dosh in your pocket, then you can start to arm yourself in case you need a bit more firepower.
First is an "emergency backup" loadout: 401+101+Pulverizer. Don't get cocky with your Pulverizer, since this should be your last resort for the most desperate situation. When your team failed to handle Fleshpound, your berserker will be the first one to tank it; If he falls in the process, the commando and support should be the next to tank hits; In case they didn't make it either, then it's your turn to use the Pulverizer to fight back. Normally you don't need the Pulverizer, and when you need it, it's already FUBAR, but eventually it may help.
Then we have a BOSS wave loadout: 401+SCAR+DE. In most case, you should be the last one to fall in the BOSS battle, and this is for you if you were the only one left to turn the tide. There's not much to say, you get a lot of ammo and firepower from the loadout, so you still stand a chance to beat Hans or Patty.
However, your best weapon is always your healthy teammates, so if they are really nice persons that you want to keep they all alive and kicking, here goes the full healing loadout: 401+301+DE. You can't go wrong with this build in any circumstance unless your teammates go wrong. You will have maximum healing potential with this loadout, so make sure everyone is healed!