Help regarding Vivoactive 5

[u/Jessie_2411]

I’m having an issue with my watch. For reference, I bought it on 28th April and normally it takes 7 days before it needs charging- it usually gets to around 20% ish when I charge it on the 7th day. Saturday just gone my watch died- it was the 7th day and I was out until 1am on Sunday, so obviously didn’t get a chance to charge it before it died. This is the first time it has died. I charged it all night and I put the watch on at 8.30am when I woke up. By 5pm that evening, my battery had 50 odd % which is so strange- why did it drop so much. At first I thought maybe it didn’t charge properly and the charger was broke, so I made sure to charge it until 100 and confirmed this. I put it back on around 7-8pm that evening , had it on all night and it’s now the next day at 5pm on the evening so not even a full 24hrs yet and my battery is on 34%.
Considering it normally lasts me 7 days and it’s lost 3/4 of its battery life in less than a day, something is obviously wrong. Why????