Assess what may have changed. You say she's going out with a different ride. Maybe she feels insecure with the new horses. My horse is a dream to hack out with others, but if she's in front or on her own she is nervous and spooky - she relies on the rest of the 'herd' to be on the lookout for danger and trusts their judgement when scary things appear (like a tractor - if no other horse is spooky then she knows it's safe and sees no reason to be afraid). When she's on her own she has to figure things out for herself, and all of a sudden normal things become scary.

Sounds like your horse needs her confidence building, and this will just take time and patience. Shorten your hacks for the time being, so she doesn't have to cope for such long periods. Then take her places on her own, walk in-hand with her and do some desensitizing with her. For example, get her used to umbrellas and wheelie bins and such. The more weird stuff she sees and has to figure out for herself, the more confidence she will get in herself.

Are there any other differences? Maybe she's not doing as much work but is on the same energy levels in her feed, thus she's got excess energy when you go out. Perhaps the quality in hay or haylege or grass has increased, again, giving her more energy. Have there been any other changes that would make her unsure - new neighbours, change of stable, change of tack?

Just have patience, try and figure out what the reason is and then deal with the problem. Good luck.