I encourage you to visit my office to discuss your difficulties. You will always be welcome. But here are some questions you can ask yourself to help you to self-diagnose your problems.
Do I attend class daily, asking questions and making the effort to understand what is taught? If your answer is no to this question, then ask yourself why you enroll in a course without the commitment to learn. Learning requires your commitment of effort and time.
Am I spending at least two full hours (with social media, tv and radio turned OFF) every day working out homework problems with paper and pencil? If your answer is no to this question, then I think you know why your grade is disappointing. There are no short-cuts to success in this course. Your objective here is to learn to solve problems yourself. This can be done only with a great deal of time in sustained concentration and effort practicing.
Do I have a notebook containing my own hand-written solutions to every homework problem that has been assigned? If your answer is no then now you know a clearly defined procedure for improving your grade dramatically. If you do not know how to solve a problem, or if you solve it incorrectly when it is assigned, you need to try again to solve the problem yourself after finding out in class or in my office or from a tutor how to do it. You should close your notebooks and try again and again to solve the problem correctly until you get it. The alternative is to find out on tests that you have not put enough work into solving the homework problems.
When I am busy or short of time, do I substitute reading a solutions manual for solving problems myself on paper? If your answer is yes then I urge you to get rid of your solutions manual. Reading another person's solutions to problems is no substitute for sweating them out on paper yourself. How do you think the author of the solutions manual learned to solve the problems? I guarantee you it was not from reading a solutions manual!
Do I buy homework solutions from an online website? The result of this practice is likely to be that you will have to repeat the course, paying tuition a second time for a course you could have passed by your own work the first time.
Do I have a job, personal difficulties, and/or so many other courses to take this term that I cannot possibly follow the advice in the items listed above? If this is the case then you have a serious decision to make now, because soon it will be too late to catch up with the work in this course. Even if you repeat this course several times, you will not earn a satisfactory grade in it until you put in the work solving problems yourself. If you don't have time to do the work this semester, then you should drop this course and take it again in a subsequent semester when you have more time and energy to commit to it. But be aware that the longer you wait, the rustier your technique from prerequisite math courses will become! If you must pass this course this term, then you will need to drop some other activity to make the time you need to do the work. There isn't any other way.