the feeding problems you describe are behavioural problems not eating problems, and a lot of us have had the same issue with this breed. Basically you need to do this :
Choose a good quality food and stick with it. Do NOT switch around if the dog refuses food. Instead, you need to regain control of the feeding sessions by not offering choices. Basically, your dog has learned that refusing food gets lots of attention from you, probably a bit of fussing and cajoling to eat, and then -- what fun! -- a new type of food. All this is a great game and very rewarding for the dog. So you want to break ALL associations between food and social interactions with you. So do this exactly every single day and I will bet you will have a dog eating normally within 3 days to a week.
1) Prepare the dog's bowl without ANY interaction with the dog -- do not talk to her, look at her, nothing. You pick up the bowl, place the food in the bowl, and without any comment, set it on the ground. The dog now has exactly *10 minutes* to eat. Totally ignore the dog during this time regardless of whether she eats or not.
2) At 10 minutes, you go and pick the bowl up and put it away. Do NOT interact with her, talk to her, fuss over here, speak to her, make eye contact. Then go back about your business for at least 10 minutes before you again can interact with her. But only interact normally -- NOTHING to do with food, praising, scolding, nothing.
3) Until the next scheduled meal do not feed her a single thing. Not a treat, nothing. In particular do NOT try to see if she will finish the bowl of food she didn't eat earlier.
4) At the next *scheduled* feeding, repeat the above.
A dog can easily go several days without eating with no problem (indeed their guts are actually designed to eat in this way) so if she won't eat she needs to learn the consequences are NO FOOD. Not new, more interesting food, or attention from you, or treats instead. Zilch.
It sometimes helps to consider what you'd do if this was a child refusing to eat. No parent would rush about making completely new dinners each meal because a child is refusing to eat, and we'd also recognise the child was being seriously manipulative in order to get attention, and that the problem was not the food. Indeed most people find that if they have a problem eater dog that goes to stay with a relative or at a kennel while they go away, lo and behold the dog eats everything it is given and anything it is given. Why? Because the new person feeding the dog isn't seen by the dog as part of the game.
Another tip is to start feeding just a single daily meal.