Unusually SUPER heavy period

So my period showed up a week and a half early (Sunday). I have been heavy bleeding since Monday.... Like 'only getting 2 hours out of an ultra tampon before leaking and when I take it out thumb sized clots exit me and are also attached to said ultra tampon' heavy.

I've NEVER had this happen before.

I saw my doctor on Wednesday as I was concerned about the early arrival (WebMD is the worst, and I should know better), but she said she wasn't concerned as I have the nexplanon implant and apparently people who use it can get erratic periods. I'm on year 2/3 with this one, and had one for the 3 years before - never an issue like this.

Anyone else have this happen? Thoughts on what do to? I'm not in any pain, it's just annoying to have to get up every 2 hours and PRAY I didn't leak....

Also: I tried using the softdisc since I'm tired of not being able to have sex for a week out of each month and tampons can be a real bitch if they're only good for 2 hours. I cannot for the life of me get it to stay put. It'll stay for like an hour and then suddenly is like Niagra falls.... My underwear cannot take this abuse! Tips on that front also greatly appreciated.

Thanks!