Follow-up explanation.
Most of the advice given out on the issue of meditative induced empathy is complete crap.
Empathy is generally useless outside of gauging another person's intention, environmental factors or tuning the frequency of an energetic form you are actively working with. It is what we don't know about others that allows us to work with them.
The meditative/yogic practices are mechanical in nature. While they harness processes that are not well understood, on which virtually no science is available, they follow very predictable rules. As such an engineering approach to dealing with them works best.
Whenever running into a problem, first identify what is causing it. Then attempt to manipulate the underlying mechanism. Repeat.
The emotional effects are astral/semi-physical in nature, as such are neither physical or mental, and generally indicative of a malfunction. The solutions are usually physical in nature. Over concern with emotions is almost always a waste of time. Address the physical mechanism causing the problem.
Certain Buddhist schools utilize a releasing technique that can be helpful dealing with the energetic swings involved that closely resemble bipolar issues. For a secular version of this look up the Sedona Method (
http://www.sedona.com/Home.asp). They overstate the technology a bit, but it works. The downside is that you have to catch yourself in the moment to employ the technique, which circumstances dependent can be tricky.
The hard part is usually figuring out what is causing the issue.
On a practical note, energetically speaking when my reserves are low I go into a magnetic state and start to draw inward, which generates a lot of empathy.
The solution is to go into electric/projection mode which requires more reserves. The role of fitness in this cannot be understated either. And is usually a major short coming in a lot of practitioner's background. Hence the use of exercise. The wire beater exercises also push energy out as well. Doing THREE repetitions of the healing sounds per organ is helpful as well. Total time should be less than 30 minutes and needs to be done daily in the morning. Just like brushing your teeth.
As you mentioned smell being a major trigger this would suggest either an earth, or water, body type. As such, a purely electric form of exercise would be most valuable in terms of maintaining stability. For this reason, I would highly recommend taking up Olympic weightlifting 2-3x per week. Sprints would work well too, but over time the injury factor can become a problem. Masters lifters in Olympic circles last forever and helps maintain body composition as well.
Outside of this I am familiar with 2-3 other meditative solutions, but they all come with significant downsides or are at least temporarily very unpleasant.
Also keep in mind that virtually all meditative work functions by converting vital force/jing into more subtle forms of energetic expression. As such they are inherently draining and push a practitioner into a magnetic/yin/empathic state.
Look up Franz Bardon's first book
Initiation into Hermetics for a Western approach to the issue.
Best of luck.
Peacedog