It is nothing unusual, it can be in fact a testing time for you - whether you will perservere in your faith when the enthusiasm is gone and you are no longer on fire. Even mystics went through Spiritual Night - that is not to say that you are going through the same, but it is a very normal thing in our spiritual journey .So what can you do? Just perservere and be faithful as long as God will wish for you to remain in that state. Read maybe the diary of St Faustina, not in the hope that the present state will go away, but to see how she coped with her experience of Spiritual Night.
There is also another possibility, sometimes when we undergo a conversion, we are all on fire and full of enthusiasm, but we overdo it, we forget that we are mortals and that our life is not only prayers and spiritual things, but also work, friends and duties and as a result we might become soon burnt out. Because even comtemplative monks/nuns spend a lot of time just working, for lay poeple, wiht no spiritual guidance - there is this danger of livign in the clouds