Confused: Feanolla/Desogestrel

[GemmaAHod17]

Hi, not sure if I'm going mad but here goes.......

Been on the POP pill for over a year now, go every 3 months to check everything is OK with the pill I'm using (no pain the legs, blood pressure, headaches etc)

I'd been taking Feanolla for 6 months+ fine no problems, no bleeding no headaches, fab.

Now when I've picked up my prescription last week its a different box with just Desogestrel on the box. (i remember having this when i first started taking the pill and had irregular bleeding, headaches and feeling really poop about myself)

A few days of taking it I've been constantly spotting/bleeding and stomach cramps.

Just a bit confused as to why this particular pill does this and the other doesn't when they both contain the same amount of desogestrel.

Thank you
Gemma