16 year old with seizure like activity

My 16 year old daughter gets extreme nausea then about 2-3 minutes later has seizure like activity…eyes rolling back in her head, stiff legs and arms and her hands draw inward, wetting herself and slight jerking. They last about 30 seconds but when she comes out of it she is completely aware of her surroundings and no longer has the nausea. She is not tired and is able to go about her normal activities. There are no triggers and they happen randomly, she might have them a couple times a month then it might be 6 months before she does it again. We have been to numerous doctors and have had many tests, including EEG and MRI which all come back clear. Her neurologist says she is just fainting but we feel like there is more going on. We are desperately trying to find some answers for not only us but her. The doctors don’t seem to want to help. They just tell her to drink plenty of fluids which she already does. This has been going on over 3 years now and are getting more frequent. Any help would be greatly appreciated.