Bang on, those 1mΩ resisters could definitely be a part of the problem.
High Impedance Analog Circuits are always susceptible to noise.
As far as decoupling goes it's always a good idea to start with low value high grade caps that properly filter out high frequency noise. Next we can add higher value caps like 10µf or higher Electrolytes'. This is standard practice especially in computers and older digital technologies. This article has nothing to do with Analog Circuits but the principles explained in it apply to any and all types of electronic circuits. In a nutshell Chip Output Switching and Interconnects such as wires and even circuit board traces have resistance, capacitance and inductance that add to digital noise getting where it shouldn't.
http://www.vagrearg.org/content/decoupling
There are two main reasons to start off with smaller value, high grade caps.
Size and filtering. Electrolytic Caps are terrible at filtering out high frequency noise and they are large.
Smaller high grade caps filter out these high frequencies and don't substantially increase your board size.
Thanks