Hi there - yes it could be the switch to continuous progestogen causing you to feel like this as it can cause continuous low-grade progestogenic side effects ie pms - in some women - when taken all the time.
There is usually no reason to stop sequi HRT just because you are 58 - there are several of us in our 60's still on cyclical HRT because of the effects of taking progestogens continuously (I am 65 and on a cycle still - although fed up with it - but needs must!). However if you have fibroids that are causing problems or endometriosis or other bleeding problems then continuous combined HRT is usually advised. There is a small increased risk in endometrial hyperplasia and therefore cancer when taking cyclical HRT but provided you have no abnormal bleeding and the balance is right then continuing with the cyclical regime should be fine for many (most?) women.
If you were happy before and no medical issues then I would ask to switch back...
Not sure how the Fluoxetine affects things too? If it was given for menopausal/hormonal depression then this is not indicated anyway and you might be better off coming off it and trying to get the HRT sorted?
Hope you feel better soon
Hurdity x