Teething and growth spurts can cause babies and toddlers to not want to eat. What I used to do is give my baby a cool damp rag to chew on (or any soothing cooled teething toy) about half an hour before feeding time. By the time it's mealtime the gums were feeling ok and she was more likely to want to eat. Mind you, it didn't work all the time but a lot of times it did. It could also be the type of food given, if it's too chunky it may cause baby to gag. My daughter, even still at 15 months, will gag on mashed potatoes. She eats regular cooked cubed potatoes like a pro, but mashed she hates and gags on it. If you don't succeed with babyfood from a jar you can aways resort to cereal made a little watery (which is full of vitamins too) and see if she'll eat that.
I see that the poster below me suggested you not feed your baby solids. I'm sure she means well and has her reasons, but you need to do what you feel you should. Here's the other side to that debate about solids. Although it is true that babies don't necessarily need the nutrition, the most important part of eating at this point is learning all the small motor skills involved in doing it. At some point your baby will learn to grab her own food with her hands and put it to her mouth, she'll learn to chew bigger chunks of food and move them around her mouth with her tongue to prevent choking. She will learn to sort her food and even throw it. There are so many educational opportunities in just the simple act of feeding your baby that I personally feel it's very important early in life. Most doctors recommend starting solids between 4-6 months old or when your baby learns to hand feed herself at the latest. Some parents choose to wait till a year old and that's fine too.
We all read lots of things in books and hear lots of different things from our doctors, you kinda just have to go with what you feel is necessary and you shouldn't be made to feel badly about the choice you do make. What's better, to find out your kid is allergic to peas at 5 months or 1 year? Does it matter? As far as I know obesity is caused by overeating, not by how early you start solids, as long as you are feeding your child the correct serving sizes and not giving her junk she'll be great. I'm more likely to believe that obese babies come from moms who stuff their kids with cereal in their bottles to keep them quiet at night or help them sleep longer. Breastfed babies tend to be able to better tell when their tummies are full and stop eating and are way less likely to overeat than a bottle fed baby. This whole thing about immune system and all that...well, genetics and environment have a LOT to do with that, more than solid food. You're doing great for your babys body just by breastfeeding, so yay!
Don't worry about your girl, she won't starve. You mentioned nursing I think. My daughter, when she was teething really badly, would nurse all day long and want no food or anything, just nursing. If you put ice on your nipples and make them really cold right before latching your baby then it will soothe her gummies right up and she'll eat happily. She'll be fine, it's just a phase. If you get more concerned and she continues like this for more than two weeks and you begin to realize she's losing weight, then call your Pedi and talk with them. **hugs** Good luck!