The assumption is that you are trying to use an enema to clear out a worm infection in your colon. While this may make theoretical sense, it is not really a recommended method of ridding yourself of worms. This is because the worms could exist in any part of your large intestine and an enema may not be able to send a potent drug that far up your colon. It is therefore better to just take so oral medication for worms as these are highly effective in dealing with the problem of worms. However, on the off-chance that the worm infection might be closer to the rectum than further up, there are a few things that you can add to an enema solution that could possibly be of some help to you.
Worms end up in the digestive tract because of oral ingestion of feces that contain worm eggs. This can happen because of improperly washing vegetables that are fresh from farms, eating meat from infected animals, drinking worm egg-infested water, and in the case of some worms in the tropics, just standing in a pool of water with worm larvae in it. In cases of oral fecal ingestion, the worm eggs hatch in your stomach and go on to settle in your intestines. A worm infection could last a few years in your intestine before the worm dies and finally falls out. In that time, you could end up being quite malnourished from the infection.
To the question of clearing your system of the worm, you can try by creating an enema solution that contains neem oil and clove oil. However, whether this would be safe to use as is can only be answered by a doctor. Ideally, you should be on a drug called albendazole, which is a wide-spectrum anti-worm drug. The other option that you can exercise, along with this treatment, is to start consuming cloves in the form of oil or as whole cloves. Clove is toxic to worms and is useful in this regard. You should also increase your intake of raw garlic, perhaps mashed with the clove oil to avoid a bad taste in the mouth. This treatment should be continued for at least a month until you start to gain weight again. It is important that you eat food with a lot of fiber at this time so that feces are not stuck in your colon.