1992 Mazda Protege power drain after a few days of running

I'm not sure if this is an electical problem or enigine?

After a few days of starting ok and driving ok my car will just not start and hold a charge. I have replaced the battery and the Alternator and after a few days it will not start. I've took it to a shop and they said to replace the alternator and I have, but it still is having the problem of not starting back up. When I put the battery on the battery charger or if I get a jump from another person, It will run untill I turn the car off but right when I try to start the car back up it will not turn on.

thank you.