To overheat or not to overheat...

I've been having troubles lately about my MacBook Pro 13" 2011 overheating. I've noticed this begun from about January 2016 to now. It takes 15 minutes and bam it's searing hot. Currently my laptop sits on my cool metal desk yet overheats.

When it gets hot it's at most 185 F. Right now it's personal lowest is 128 F running the exact same programs when it overheats.

Possible reasons

I've found that causes of overheating could be from overworking the computer with too many process.

I went into the activities monitor and ended any unnecessary programs and still my computer was burning. I leave on just 1 application, nothing has changed.

2. Another could be a build up of dust which messes with the fan.

I personally went in and blew out as much dust as i could and still the computer would burn up.

I took the liberty of placing a fan underneath the computer even though it burns up it stays cool to a certain degree but in some areas scorching hot.

Now, June 16, i'm sitting in my basement casually using my laptop on my lap while it's charging. I look at it's temperature. Cooler than it was with the fan underneath it. Now i'm upstairs writing about this on my lap and it's cool.

I'm sure this isn't the first time it has been cool but for just this week the overheating has been getting on my nerves.

Now i'm totally clueless to why my computer is overheating.