1998 Toyota 4Runner engine noises

I have a 98 4runner 6cyl. About 2 weeks ago I noticed it making a noise, it was not loud and it sounded kinda like a knock or a vacum leak. I thought it might be a leak in my exaust manifold. Now 2 weeks later the noise is alot louder and it sounds like more of a knock I think. I should tell ya that I had my oil changed on the 2nd of jan with 5w30 an then they put a court of 10w30 in to fill the rest. I dont think that would really make a difference but I still changed it again anyway + I put in the lucas additive stuff, I always do and all 5w30 valvoline. I dont no if I gave enough info but with what I have so far can ya point me in a direction. Just not in the rod direction please. I hope. Thats last. I dont no what a bad valve would do, or timing?