Continual Drain Clogs

It was a supris to me that within days of clearing a sink clog in my bathroom that clog returned. I used drain cleaner again and it onyl stayed clear for a couple of days. I don't want to keep pouring chemicals down my drain, but how do I repair the clog? Do I need to take the pvc pipe apart? I am a novice when it comes to this stuff and I bet I'll be suprised when I find our what's in there. Thanks in advance for any advice.
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