Will acne & cystic spots get better after tretinoin for anti-ageing ruined my skin?

It was likely way too irritating to your skin. You could give it a few more weeks to see if it continues to improve or go ahead and see your doctor. You may need some treatment to settle down this flare. I would suggest bakuchiol for your anti-aging needs moving forward. It has similar effects to tretinoin without irritation. You could potentially try tretinoin again easing into very slowly taking steps to minimize the irritation. So starting once a week and building slowly up to 2 to 3 x per week. Being sure all the rest of your products are hydrating and using moisturizer immediately on top of the tretinoin. Should also wait 30 minutes after washing and drying face to apply the tretinoin. Lastly, using only a pea size for the whole face. Or try bakuchiol.