sounds like you might have an ovarian cyst
or a late ovulation.
Why do I think this?
Sometimes you can " miss" an ovulation - what can happen is that the cyst that is supposed to ovulate doesn`t and then it can either get smaller and dissappear or just get bigger and bigger.
The cyst that gets bigger can produce a lot of estrogenes ( female hormones) and this can cause a build up of cervical secretion - which can in effect look like jelly - it gathers inside the opening of the cervix
and can then be released in large lumps or a large jelly like lump.
Often this might occur when the larger cyst does rupture - later than normal.
This could cause backpain.
can be caused by a lack of progesteron - and estrogene dominance ( from the cyst).
You should expect your period to come within the next 2-3 weeks.
You shouldn`t worry about this - this often happens.
In a nutshell: no ovulation midcycle - cyst doesn`t ovulate and grows bigger - producing estrogenes - that can cause an estrogene dominance - headaches, breast tension, feeling bloated, weight gain, extreme vaginal jelly like discharge, pain -
But just to make sure - check with your doctor.
The cyst still might be there and growing bigger.
all the best!