Triple eyelid! What can I do to have my previous double eyelids back? (Photo)

Recently I realise that I have a triple layer eyelid on my left eye. It gets worse if I don’t sleep enough or have a migraine attack. Then slowly this triple eyelid became a semi permanent fixture on my eye. It bothers me as I am starting to take more effort to open my left eyelid and also blink purposely to “adjust” the lids. What causes it? Is it my regular Botox? Or am I just ageing? What can I do to have my previous double eyelids back? Thank you