dog snapped at other dogs a few times this week.

[ditavonteesed]

never done it before, gone up to dog to say hello started nicely and then just turned, has happened 4 times this week, all on the lead. the first couple of times I was trying her with a gentle leader so figured it was this and took it off, today she has said hello to loads of dogs nicely and then a couple of dogs also on lead came to say hello (same breed as her as was the one earlier in the week, dont know if relevant) and she snapped.
I dont really know how to handle it, darent let her off the lead which is a pain as she loves a good run.

Any advice really dont want this to develop.
TIA

Take her to the vets for a check up. Could be an ear infection or something similar. If all okay then I'd take out treats with me so she associates meeting other dogs on leads as a good thing ie I get a treat. Disclaimer - I am no dog expert.

Is she neutered? My lab bitch does this just before she comes into season. Not to all dogs, but particular ones that we see regularly when we're out for a walk she seems to take a real aversion to during that time.

Canine PMT .

I took her out early this morning so I knew there wouldnt be many poeople around so she could be off lead, played lovely with the few dogs we saw and was fine, lots of clicker training kept her occupied.
just took her out again and had her mainly off lead doing a lot of traiing again, she was fine, saw one iof the dogs that she has snapped at, she was absolutly fine with dog and man didnt even remember, think she may have been a bit stressed, park was crowded and she was stuck on lead, in future think will leave her at home when taking kids to park.
will be extra cautious and going to see how she is at training tommorow. thanks for the replies.
She is spayed so not pmt (maybe kids are off school moods or are they just mine).